In U.S. Pat. No. 3,951,435 (Greatbach), a vehicle coupling is provided which include two members for coupling a tractor to a trailer. One member comprises an A-frame which is pivotally attached about a horizontal transverse axis to the tractor. This A-frame member is further pivotally attached to the trailer through a two degree rotational coupling which allows rotation about a horizontal longitudinal axis and a vertical axis.
Various universal type trailer hitches have also been disclosed in the prior art. Examples of such hitches include these shown in the following U.S. Pat. Nos. 1,934,141 (Prentice); 2,027,499 (Tully); 3,730,557 (Cox); and 3,680,892 (Olthoff et al).
Another towing connection which provides three degrees of movement is disclosed in U.S. Pat. No. 2,937,886 (Poole). This towing connection includes a bifurcated beam which is connected to a tractor at the two ends thereof for rotation about a horizontal transverse axis. The other end of the bifurcated beam is mounted for rotation about a horizontal longitudinal axis in a yoke. Extending upwardly from the yoke is a vertical axle about which a goose necked tow bar for a trailer is coaxially received.
Disclosed in U.S. Pat. No. 4,433,853 (Swaim) is a convertible trailer hitch for towing a trailer or the like. The hitch includes a goose neck arm braced by an A-frame tongue. The goose neck arm can be used for towing, or the goose neck arm can be pivoted out of the way and locked into position and the A-frame tongue used for towing. Another adjustable goose neck towing hitch is disclosed in U.S. Pat. No. 4,015,549 (Brown, Jr.), where an upstanding landing leg is provided adjacent the towed implement.